lecture 5 telecommunications, internet & wireless technology

Lecture 5: Telecommunications and the Internet; Prepared by Zaved Mannan of 11

Lecture 5

Telecommunications, the Internet and Wireless Technology

WHAT IS A COMPUTER NETWORK?

• Each computer on the network contains a network interface device called a

network interface card (NIC). Most personal computers today have this card

built into the motherboard.

• The connection medium for linking network components can be a telephone

wire, coaxial cable, or radio signal.

FIGURE 7-1 COMPONENTS OF A SIMPLE COMPUTER NETWORK

• A server computer performs important network functions for client

computers, such as serving up Web pages, storing data, and storing the

network operating system and hence controlling the network.

Essential Reading

Textbook, Chapter 7

Optional Reading

Reading 9.1 Haag, S., &Cummings, M. (2009). Emerging trends and technologies. In Management

information systems for the information age (7th ed., pp. 403-428). New York: McGaw Hill.


• Server software such as Microsoft Windows Server, Linux, and Novell Open

Enterprise Server are the most widely used network operating systems.

• The network operating system (NOS) routes and manages communications

on the network and network resources.

• A switch or a hub acting as a connection point between the computers.

• Hubs are very simple devices that connect network components, sending a

packet of data to all other connected devices.

• A switch has more intelligence than a hub and can filter and forward data to

a specified destination on the network.

• A router is a communications processor used to route packets of data

through different networks, ensuring that the data sent gets to the correct

address.

• You would need a router to access internet.

Networks in Large Companies

• Corporate-wide networking infrastructure: hundreds of small local area

networks.

– Using cell phones and smartphones,

– Using mobile wireless local area networks (Wi-Fi networks)

– A videoconferencing system

– a separate telephone network that handles most voice data.

– using Internet telephones

• How to integrate all the different communication networks and channels into

a coherent system that enables information to flow from one part of the

corporation to another, and from one system to another.


Packet Switching

• A method of slicing digital messages into parcels called packets, sending the

packets along different communication paths as they become available, and

then reassembling the packets once they arrive at their destinations (see

Figure 7-3).

• Prior to the development of packet switching, computer networks used

leased, dedicated telephone circuits to communicate with other computers in

remote locations.

• But they were expensive and wasted available communications capacity—the

circuit was maintained regardless of whether any data were being sent.

FIGURE 7-3 PACKED-SWITCHED NETWORKS AND PACKET COMMUNICATIONS

TCP/IP

• Components in a network communicate with each other only by adhering to a

common set of rules called protocols.

• A protocol is a set of rules and procedures governing transmission of information

between two points in a network.

• Corporate networks are using a single, common, worldwide standard called

Transmission Control Protocol/Internet Protocol (TCP/IP).

• TCP/IP was developed during the early 1970s to support U.S. Department of Defense

Advanced Research Projects Agency (DARPA)

FIGURE 7-4 THE TRANSMISSION CONTROL PROTOCOL/INTERNET PROTOCOL


(TCP/IP) REFERENCE MODEL

• TCP/IP uses a suite of protocols.

• TCP handles the movement of data between computers.

• TCP establishes a connection between the computers, sequences the transfer of

packets, and acknowledges the packets sent.

• IP is responsible for the delivery of packets and includes the disassembling and

reassembling of packets during transmission.

SIGNALS: DIGITAL VS. ANALOG

• An analog signal is represented by a continuous waveform.

• The most common analog devices are the telephone handset, the speaker on your

computer.

• A digital signal is a binary waveform, rather than a continuous waveform: one bit

and zero bits or on-off electrical pulses.

• Computers use digital signals and require a modem to convert these digital signals.

FIGURE 7-5 FUNCTIONS OF THE MODEM

• Modem stands for modulator-demodulator.

• Cable modems connect your computer to the Internet using a cable network.

• DSL modems connect your computer to the Internet using a telephone company’s

land line network.

• Wireless modems connecting your computer to a wireless network that could be a

cell phone network, or a Wi-Fi network.

• Without modems, computers could not communicate with one another using analog

networks (which include the telephone system and cable networks).

Types of Network

• LAN:

– Connect few computers, half-mile

– Link to other networks.

– One computer is dedicated file server.

– The server determines the access.

– Router connects LAN to other networks.

– Common LAN OS: Windows, Linux, Novell

– Ethernet (10 Mbps) is the physical medium to carry signals between

computers.

– Fast Ethernet (100 Mbps) or Gigabit Ethernet (1 Gbps).

– Larger LAN have many clients & servers.

– File server, database servers, print servers, mail servers, web servers, etc.


– Topology: LANs are described in terms of the way their components are

connected.

Type Area

Local area network (LAN) Up to 500 meters (half a mile); an office or

floor of a building

Campus area network (CAN) Up to 1,000 meters (a mile); a college

campus or corporate facility

Metropolitan area network

(MAN)

A city or metropolitan area

Wide area network (WAN) A transcontinental or global area

TABLE 7-1 TYPES OF NETWORKS

– Star topology: traffic flows through a single hub. Extended star network.

– Bus Topology: Most common. Signals are broadcast in both directions. Same

signals.

– Ring topology: Traffic flows only in one direction. One station at a time

transmit.

INTERNET ADDRESSING AND ARCHITECTURE

• Every computer on the Internet is assigned a unique IP address

• IP represents a 32-bit number (0 to 255)

• www.microsoft.com is 207.46.250.119.

• It’s difficult for users to remember numerical IP.

• The domain name is the English-like name that corresponds to numeric IP.


• the Domain Name System (DNS) converts domain names to IP addresses.

• DNS maintain a database containing IP addresses mapped to their corresponding

domain names.

FIGURE 7-8 THE DOMAIN NAME SYSTEM

The Domain Name System

• .com Commercial businesses

• .edu Educational institutions

• .gov U.S. government agencies

• .mil U.S. military

• .net Network computers

• .org Nonprofit organizations

• .biz Business firms

• .info Information providers

IPv6

• The Internet was not originally designed to handle billions of users.

• Big users of Internet: large corporation, govt. & billions of users.

• The world will run out of available IP addresses by 2012 or 2013.

• New version of the IP addressing schema called Internet Protocol version 6 (IPv6),

• It will contain 128-bit addresses or more than a quadrillion possible unique

addresses.

Internet 2

• Internet2 and Next-Generation Internet (NGI) are representing 200 universities, &

other org in the USA

• They are working on a new, robust, high-bandwidth version of the Internet.

• They have new high-performance backbone networks with bandwidths reaching as

much as 100 Gbps (normal is 45 mbps to 2.5 gbps)


• Internet2 research groups are developing and implementing new technologies for

more effective routing practices; different levels of service.

• These networks do not replace the public Internet, but may eventually migrate to the

public Internet.

Web 2.0

• Web 2.0 services:

– Sharing photos at Flickr ,

– Posting a video to YouTube,

– Creating blog,

– Using Wikipedia,

– Adding a widget to your Facebook page

• Web 2.0 has four defining features:

– Interactivity,

– Real-time user control,

– Social participation (sharing), and

– User-generated content.

• The technologies and services includes:

– Cloud computing, software mashups and

– Widgets, blogs, RSS, wikis, and social networks.


Web 3.0: The Future Web

• Web 1.0 :access to information.

• Web 2.0 :sharing that information with others, and building new Web experiences.

• Web 3.0 :future Web where all this digital information, all these contacts, can be

woven together into a single meaningful experience.

• Google or Yahoo search: What you get?

Semantic Web.

• “Semantic” refers to meaning.

• Google search: First, enter “Paris Hilton”. Next, enter “Hilton in Paris”.

• Google doesn’t understand the meaning of Hilton or Paris.

• future Web vary generally focus on ways to make the Web more “intelligent,”

• with machine-facilitated understanding of information

• effective user experience.

Cellular Systems

• Earlier generations of cellular systems were designed primarily for voice and limited

data transmission in the form of short text messages.

• 3G: transmission speeds from 144 Kbps to more than 2 Mbps.

• 4G: capable of 100 Mbps transmission speed with premium quality and high security.

– Voice, data, and high-quality streaming video will be available to users

anywhere, anytime.

WIRELESS COMPUTER NETWORKS

Bluetooth

• Useful for creating small personal area networks (PANs).

– It links up to eight devices within a 10-meter area

– Use low-power, radio-based communication

– Can transmit up to 722 Kbps in the 2.4-GHz band.

• FedEx drivers use Bluetooth to transmit the delivery data captured by

computers (‘PowerPad’) to cellular transmitters, which forward the data to

corporate computers. Bluetooth has saved FedEx $20 million per year.

Wi-Fi

• In most Wi-Fi communication, wireless devices communicate with a wired LAN using

access points.

• An access point is a box consisting of a radio receiver/transmitter and antennas that

links to a wired network, router, or hub.

• Mobile access points such as Virgin Mobile’s WiFi use the existing cellular network to

create Wi-Fi connections.

• Figure illustrates an 802.11 wireless LAN that connects a small number of mobile

devices to a larger wired LAN and to the Internet.


•

FIGURE 7-15 A BLUETOOTH NETWORK

• Wi-Fi

• Most wireless devices are client machines. The servers that the mobile client

stations need to use are on the wired LAN.

• The access point controls the wireless stations and acts as a bridge between

the main wired LAN and the wireless LAN.

• A bridge connects two LANs based on different technologies.

• The access point also controls the wireless stations.

• Hotspots typically consist of one or more access points providing wireless Internet

access in a public place.

• Some hotspots are free or do not require user account activation.

• Businesses of all sizes are using Wi-Fi networks to provide low-cost Internet access.

• Hotels, airport lounges, libraries, cafes, and college/uni campuses have mobile

Internet access.

• Wi-Fi’s security features make wireless networks vulnerable.

WiMax

• A surprisingly large number of people worldwide do not have access to Wi-Fi or fixed

broadband connectivity.

• The range of Wi-Fi systems is no more than 300 feet from the base station

• Difficult for rural groups that don’t have cable or DSL service to find wireless access

to the Internet.

• The IEEE developed a new family of standards known as WiMax to deal with these

problems.

• WiMax (Worldwide Interoperability for Microwave Access) is the popular term for

IEEE Standard 802.16.

• It has a wireless access range of up to 31 miles and transmission speed of up to 75

Mbps.

• WiMax antennas are powerful enough to beam high-speed Internet connections.

• Cellular handsets and laptops with WiMax capabilities are appearing in the

marketplace.


FIGURE 7-16 AN 802.11 WIRELESS LAN

• Mobile WiMax is one of the pre-4G network technologies.

• Clearwire use WiMax technology as the foundation for the 4G networks in the United

States.

RFID

• Radio frequency identification (RFID) systems provide a powerful technology for

tracking the movement of goods throughout the supply chain.

• Automated toll-collection systems such as New York’s E-ZPass use active RFID tags.

• RFID is used in inventory control and supply chain management.

FIGURE 7-17 HOW RFID WORKS


Wireless Sensor Networks

• Wireless sensor networks (WSNs) are networks of interconnected wireless devices

that are embedded into the physical environment to provide measurements of many

points over large spaces.

• These devices have built-in processing, storage, and radio frequency sensors and

antennas.

• They are linked into an interconnected network that routes the data they capture to

a computer for analysis.

• These networks range from hundreds to thousands of nodes.

• Low power requirements.

FIGURE 7-18 A WIRELESS SENSOR NETWORK

Prepared by

Zaved Mannan

Adjunct Faculty

University of Liberal Arts Bangladesh (ULAB)

READ

Textbook, Chapter 7 (pp. 252-257, 261-267, 277-286) & lecture guide. Don’t rely entirely on lecture

guide. This is a guide only. Don’t expect good mark if you don’t read TEXTBOOK.